GW-7553-B / GW-7553-M PROFIBUS/Modbus TCP Gateway User Manual
(Version 1.35, May/2017)
PAGE: 42
If the polling speed between the GW-7553-B / GW-7553-M device and the
Modbus Slave is faster than the data exchange rate between PROFIBUS Master
and the GW-7553-B / GW-7553-M then the PROFIBUS Master will not get all
the data from the Modbus Slave and therefore a diagnostic message
(“PROFIBUS lose input data”) will be send by the GW-7553-B / GW-7553-M
to the PROFIBUS Master
b. GW-7553-B / GW-7553-M acts as a Modbus Slave
If the GW-7553-B / GW-7553-M receives more telegram from the Modbus
Master than it transmits to the PROFIBUS Master then a diagnostic message
(“PROFIBUS lose input data”) will be send by the GW-7553-B / GW-7553-M
to the PROFIBUS Master.
c. When the GW-7553-B / GW-7553-M receives a “data output command”
(output byte 0) from system setting module, and this command didn‟t increase in
order (ex: 0->1, 1->2,…, 255->0), the GW-7553-B / GW-7553-M will think that
it lose some output data of the PROFIBUS Master and a diagnostic message
(“Lose PROFIBUS output data”) will be sent by the GW-7553-B / GW-7553-M
to the PROFIBUS Master.
4.6 I/O data exchange
The I/O data exchange is decided by Modbus type of the GW-7553-B / GW-7553-
M (please refer section 4.3 The Configuration of the common parameters)
between PROFIBUS Master device and the GW-7553-B / GW-7553-M. Output
data area of PROFIBUS Master device is mapped into DO/AO memory of the
GW-7553-B / GW-7553-M and input data area of PROFIBUS Master device is
mapped into DI/AI memory of the GW-7553-B / GW-7553-M, when Modbus
type is Master. In the other way, Output data area of PROFIBUS Master device is
mapped into DI/AI memory of GW-7553-B / GW-7553-M and input data area of
PROFIBUS Master device is mapped into DO/AO memory of GW-7553-B / GW-
7553-M, when Modbus type is Slave (please refer section 3.1 PROFIBUS data
exchange ).
4.6.1 Input data area
The maximum length of input data is 240 bytes. Before arrange the input
module, the user must arrange and configure the system setting module. The
first six bytes belong to diagnostic message, as shown in
table 15.
The user can
get data and control I/O of Modbus Slave device or get DI/DO/AI/AO of the
GW-7553-B / GW-7553-M by read input module.
Содержание GW-7553-B
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